Phenolic moulding plastic and preparation method thereof

Abstract

The invention relates to the technical field of plastics, and provides a phenolic moulding plastic and a preparation method thereof, the phenolic moulding plastic comprises the following components by weight: 30-50 parts of phenolic resin, 4-7 parts of a curing agent and 3-6 parts of composite fiber; wherein the composite fibers are glass fibers coated with polyurea nanofibers on the surfaces. The polyurea nanofibers are coated on the surfaces of the glass fibers to obtain the composite fibers, good physical and chemical properties of the glass fibers are reserved, meanwhile, the polyurea nanofibers are coated on the surfaces of the glass fibers to form a protective layer, so that the properties of the phenolic moulding plastic can be enhanced, and the polyurea nanofibers are coated on the surfaces of the glass fibers to form a protective layer. The interface adaptability of the glass fiber and the phenolic resin can be optimized, and effective stress transfer can be formed between the composite fiber and the phenolic resin through good interface bonding, so that the strength of the phenolic molding plastic can be improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of plastics, and particularly relates to a phenolic molding compound and a preparation method thereof. Background Art

[0002] Phenolic resin is a kind of synthetic resin prepared by condensation of phenols and aldehydes, which has a long history. Among them, the phenolic resin prepared from phenol and formaldehyde is the most common. It has good heat resistance, excellent flame retardancy, and outstanding electrical insulation, and has wide applications in the fields of phenolic molding compounds, coatings, refractory materials, coated sand, etc. Especially as the matrix resin for preparing phenolic molding compounds, it accounts for more than 20% of its usage. The prepared phenolic molding compound is an important component material for household appliance parts, coil skeletons, insulation devices, etc.

[0003] In the prior art, in order to further improve the performance of phenolic molding compounds, glass fibers are added thereto. However, glass fibers are brittle, which limits the application of phenolic molding compounds on commutators with higher performance requirements. Therefore, it is necessary to improve glass fibers to enhance the performance of phenolic molding compounds. Summary of the Invention

[0004] In view of the above situation, to overcome at least some defects of the above prior art, the present invention provides a phenolic molding compound and a preparation method thereof.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows: The present invention provides a phenolic molding compound, which comprises the following components by weight: 30 - 50 parts of phenolic resin, 4 - 7 parts of curing agent, and 3 - 6 parts of composite fiber; Wherein, the composite fiber is glass fiber coated with polyurea nanofibers on the surface.

[0006] In some embodiments, in the composite fiber, the diameter of the glass fiber is 8 μm - 12 μm.

[0007] In some embodiments, the polyurea nanofibers are prepared by polymerization of isocyanate and amino compound.

[0008] In some embodiments, the isocyanate includes at least one of toluene diisocyanate and diphenylmethane diisocyanate, and the amino compound includes at least one of octadecylamine and cyclohexylamine.

[0009] The present invention also provides a preparation method of a phenolic molding compound, comprising: Mixing phenolic resin, curing agent and composite fiber, putting them into a twin-screw extruder, performing melt blending treatment, extruding, and molding to obtain a phenolic molding compound.

[0010] In some embodiments, the method for preparing the composite fiber comprises: Add glass fiber into an amino compound solution, stir at 40°C - 50°C for 20 min - 30 min, add an isocyanate solution, raise the temperature to 70°C - 80°C, react for 1 h - 2 h, and after the reaction, dry at 50°C - 60°C for 1 h - 2 h to obtain the composite fiber.

[0011] In some embodiments, it further comprises: before preparing the composite fiber, performing acid treatment on the glass fiber.

[0012] In some embodiments, the acid solution used in the acid treatment is a hydrochloric acid solution with a mass fraction of 5% - 10%, and the time of the acid treatment is 10 h - 20 h.

[0013] In some embodiments, it further comprises: after the acid treatment, drying the glass fiber, and the drying time is 1 h - 2 h and the temperature is 50°C - 70°C.

[0014] The beneficial effects achieved by the present invention are as follows: By coating polyurea nanofibers on the surface of glass fiber to obtain the composite fiber, the good physical and chemical properties of the glass fiber are retained. At the same time, a protective layer is formed by coating polyurea nanofibers on the surface of the glass fiber, thereby enhancing the performance of the phenolic molding compound. Moreover, coating polyurea nanofibers on the surface of the glass fiber can optimize the interfacial compatibility between the glass fiber and the phenolic resin. Good interfacial bonding can form effective stress transfer between the composite fiber and the phenolic resin, thereby improving the strength of the phenolic molding compound. Specific Embodiments

[0015] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments; based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts belong to the scope of protection of the present invention.

[0016] The following disclosure provides many different embodiments or examples for implementing different structures of the present invention. To simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are only examples and are not intended to limit the present invention. In addition, the present invention provides examples of various specific processes and materials, but those skilled in the art can be aware of the application of other processes and / or the use of other materials.

[0017] The first aspect of the embodiment of the present invention provides a phenolic molding compound, which comprises the following components by weight: 30 - 50 parts of phenolic resin, 4 - 7 parts of curing agent, and 3 - 6 parts of composite fiber; Among them, the composite fiber is glass fiber coated with polyurea nanofibers on the surface.

[0018] Glass fiber is composed of countless glass fiber monomers. The contact area between its monomers is relatively small, while the longitudinal extension length is relatively large. This structural feature makes glass fiber prone to breakage from the side or at the fiber intersection when subjected to external forces. Therefore, the properties of phenolic molding compound are poor. By coating polyurea nanofibers on the surface of glass fiber to obtain composite fiber, the good physical and chemical properties of glass fiber are retained. At the same time, the polyurea nanofibers form a protective layer on the surface of glass fiber, enhancing the strength of glass fiber, thereby improving the strength of phenolic molding compound.

[0019] At the same time, due to the poor interfacial compatibility between glass fiber and phenolic resin, when it is added as a filler to phenolic resin, there will be many micro-defects at the interface between the fiber and the resin, resulting in damage to the strength of the prepared phenolic molding compound. By coating polyurea nanofibers on the surface of glass fiber, the interfacial compatibility between glass fiber and phenolic resin can be optimized. Good interfacial bonding can form effective stress transfer between the composite fiber and phenolic resin, thereby improving the strength of phenolic molding compound.

[0020] In some embodiments, in the composite fiber, the diameter of the glass fiber is 8 μm - 12 μm. The smaller the diameter of the glass fiber, the higher the strength. However, the worse the dispersibility in phenolic resin and the easier to generate defects at the interface. On the contrary, the larger the diameter of the glass fiber, the lower the strength and the better the dispersibility. By limiting the diameter of the glass fiber to 8 μm - 12 μm, the glass fiber can have good strength and good dispersibility.

[0021] In some embodiments, the polyurea nanofibers are prepared by the polymerization reaction of isocyanate and amino compound. The polyurea nanofibers are formed by the polymerization reaction of isocyanate and amino compound. The reaction formula is: RNCO + H2N-R' → RNHC(O)NHR', where RNCO represents isocyanate, H2N-R' represents amino compound, and RNHC(O)NHR' represents the generated urea structure.

[0022] In some embodiments, the isocyanate includes at least one of toluene diisocyanate and diphenylmethane diisocyanate, and the amino compound includes at least one of octadecylamine and cyclohexylamine. Among them, toluene diisocyanate has high reaction activity and can react quickly with amino compounds to form a polyurea structure. Diphenylmethane diisocyanate also has high reaction activity and good stability, which is convenient for controlling the reaction process. Octadecylamine has a long carbon chain structure, which can endow the polyurea nanofibers with good flexibility and wear resistance. Cyclohexylamine has a cyclic structure, which can endow the polyurea nanofibers with certain rigidity and heat resistance.

[0023] The second aspect of the embodiments of the present invention provides a method for preparing phenolic molding compound, including: Mix phenolic resin, curing agent and composite fiber, put them into a twin-screw extruder, conduct melt blending treatment, extrude and mold to obtain phenolic molding compound.

[0024] Among them, phenolic resin, as the main base material of the molding compound, has good heat resistance, corrosion resistance, electrical properties and mechanical strength. During the melt blending process, the curing agent reacts with the phenolic resin to promote the curing of the phenolic resin. After the phenolic resin is cured, it has high strength and heat resistance. The material after melt blending treatment is extruded from the head of the extruder to form a continuous molten material flow. After the molten material flows through the mold, it cools and solidifies in the mold to form the required phenolic molding product.

[0025] In some embodiments, the method for preparing composite fiber includes: Add glass fiber into the amino compound solution, stir at 40°C - 50°C for 20 min - 30 min, add the isocyanate solution, raise the temperature to 70°C - 80°C, react for 1 h - 2 h, and dry at 50°C - 60°C for 1 h - 2 h after the reaction ends to obtain composite fiber.

[0026] By placing the glass fiber in the amino compound solution, a large number of amine chemical functional groups can be attached to the surface of the glass fiber. Then, add the isocyanate solution to the glass fiber dispersion, and utilize the addition polymerization reaction to realize the in-situ growth of polyurea nanofibers on the surface of the glass fiber.

[0027] Among them, the solvent of the amino compound solution can be anhydrous ethanol, and the concentration of the amino compound solution is 0.4 - 0.5 mol / L. The solvent of the isocyanate solution can be ethyl acetate, and the concentration of the isocyanate solution is 0.1 - 0.2 mol / L.

[0028] It should be noted that the reaction temperature needs to be controlled at 70°C - 80°C. Too low a temperature will lead to too slow a reaction rate, and too high a temperature may cause the product to decompose.

[0029] In some embodiments, it further includes: before preparing the composite fiber, acid-treat the glass fiber. Acid treatment can etch the surface of the glass fiber, thereby increasing the surface roughness of the glass fiber, and further increasing the attachment sites of amine chemical functional groups, which is convenient for preparing composite fiber.

[0030] In some embodiments, the acid solution used in the acid treatment is a hydrochloric acid solution with a mass fraction of 5% - 10%, and the time of the acid treatment is 10h - 20h. Since the acid treatment will corrode the surface of the glass fiber, too high a concentration of acid or too long a time will cause excessive corrosion, resulting in the destruction of the glass fiber structure. Too low a concentration of acid or too short a time will lead to poor etching effect and a reduction in the attachment sites of amino chemical functional groups.

[0031] In some embodiments, it further includes: after the acid treatment, the glass fiber is dried, the drying time is 1h - 2h, and the temperature is 50°C - 70°C. Through the drying treatment, the residual hydrochloric acid solution on the surface of the glass fiber can be removed, avoiding the influence of the residual hydrochloric acid solution on the subsequent reaction. And by controlling the drying time to be 1h - 2h and the temperature to be 50°C - 70°C, it can ensure sufficient drying while avoiding a decrease in the performance of the glass fiber due to over-drying.

[0032] The present invention will be further described below by way of specific embodiments.

[0033] In the experimental methods in the following examples, unless otherwise specified, they are all conventional methods; the test materials used in the following examples, unless otherwise specified, are all obtained from commercial channels.

[0034] Example 1 A phenolic molding compound, by weight, includes the following components: 30 parts of phenolic resin, 4 parts of curing agent, and 3 parts of composite fiber.

[0035] Preparation of composite fiber: Take 10g of glass fiber and place it in 400mL of hydrochloric acid solution with a mass fraction of 5%, acid-treat for 10h, take it out and dry the glass fiber, the drying time is 1h, and the temperature is 50°C; Add the acid-treated glass fiber into 300mL of octadecylamine solution with a concentration of 0.4mol / L, stir at 40°C for 20min, add toluene diisocyanate solution with a concentration of 0.1mol / L, raise the temperature to 70°C, react for 1h, and dry at 50°C for 1h after the reaction to obtain the composite fiber.

[0036] Preparation of phenolic molding compound: Mix the phenolic resin, curing agent, and composite fiber, put them into a twin-screw extruder, carry out melt blending treatment, extrude, and mold to obtain the phenolic molding compound.

[0037] Example 2 A phenolic molding compound, by weight, includes the following components: 50 parts of phenolic resin, 7 parts of curing agent, and 6 parts of composite fiber.

[0038] Preparation of composite fiber: Take 10 g of glass fiber and place it in 400 mL of hydrochloric acid solution with a mass fraction of 10%. Acid-treat for 20 h. After taking it out, dry the glass fiber. The drying time is 2 h and the temperature is 70 °C; Add the acid-treated glass fiber into 300 mL of octadecylamine solution with a concentration of 0.5 mol / L. Stir at 50 °C for 30 min. Add toluene diisocyanate solution with a concentration of 0.2 mol / L. Raise the temperature to 80 °C and react for 2 h. After the reaction ends, dry at 60 °C for 2 h to obtain composite fiber.

[0039] Preparation of phenolic molding compound: Mix phenolic resin, curing agent and composite fiber, put them into a twin-screw extruder, carry out melt blending treatment, extrude and mold to obtain phenolic molding compound.

[0040] Example 3 A phenolic molding compound, by weight, comprises the following components: 30 parts of phenolic resin, 4 parts of curing agent and 3 parts of composite fiber.

[0041] Preparation of composite fiber: Take 10 g of glass fiber and place it in 400 mL of hydrochloric acid solution with a mass fraction of 5%. Acid-treat for 10 h. After taking it out, dry the glass fiber. The drying time is 1 h and the temperature is 50 °C; Add the acid-treated glass fiber into 300 mL of cyclohexylamine solution with a concentration of 0.4 mol / L. Stir at 40 °C for 20 min. Add diphenylmethane diisocyanate solution with a concentration of 0.1 mol / L. Raise the temperature to 70 °C and react for 1 h. After the reaction ends, dry at 50 °C for 1 h to obtain composite fiber.

[0042] Preparation of phenolic molding compound: Mix phenolic resin, curing agent and composite fiber, put them into a twin-screw extruder, carry out melt blending treatment, extrude and mold to obtain phenolic molding compound.

[0043] Example 4 A phenolic molding compound, by weight, comprises the following components: 50 parts of phenolic resin, 7 parts of curing agent and 6 parts of composite fiber.

[0044] Preparation of composite fiber: Take 10 g of glass fiber and place it in 400 mL of hydrochloric acid solution with a mass fraction of 10%. Acid-treat for 20 h. After taking it out, dry the glass fiber. The drying time is 2 h and the temperature is 70 °C; Add the acid-treated glass fiber into 300 mL of cyclohexylamine solution with a concentration of 0.5 mol / L, stir at 50 °C for 30 min, add diphenylmethane diisocyanate solution with a concentration of 0.2 mol / L, heat up to 80 °C, react for 2 h, and dry at 60 °C for 2 h after the reaction to obtain the composite fiber.

[0045] Preparation of phenolic molding compound: Mix phenolic resin, curing agent and composite fiber, put them into a twin-screw extruder, carry out melt blending treatment, extrude and mold to obtain the phenolic molding compound.

[0046] Example 5 A phenolic molding compound, by weight, comprises the following components: 40 parts of phenolic resin, 5 parts of curing agent and 5 parts of composite fiber.

[0047] Preparation of composite fiber: Take 10 g of glass fiber and place it in 400 mL of hydrochloric acid solution with a mass fraction of 8%, carry out acid treatment for 15 h, take out and dry the glass fiber, the drying time is 1.5 h and the temperature is 60 °C; Add the acid-treated glass fiber into 300 mL of octadecylamine solution with a concentration of 0.45 mol / L, stir at 45 °C for 25 min, add toluene diisocyanate solution with a concentration of 0.15 mol / L, heat up to 75 °C, react for 1.5 h, and dry at 55 °C for 1.5 h after the reaction to obtain the composite fiber.

[0048] Preparation of phenolic molding compound: Mix phenolic resin, curing agent and composite fiber, put them into a twin-screw extruder, carry out melt blending treatment, extrude and mold to obtain the phenolic molding compound.

[0049] Example 6 A phenolic molding compound, by weight, comprises the following components: 40 parts of phenolic resin, 5 parts of curing agent and 5 parts of composite fiber.

[0050] Preparation of composite fiber: Take 10 g of glass fiber and place it in 400 mL of hydrochloric acid solution with a mass fraction of 8%, carry out acid treatment for 15 h, take out and dry the glass fiber, the drying time is 1.5 h and the temperature is 60 °C; Add the acid-treated glass fiber into 300 mL of cyclohexylamine solution with a concentration of 0.45 mol / L, stir at 45 °C for 25 min, add diphenylmethane diisocyanate solution with a concentration of 0.15 mol / L, heat up to 75 °C, react for 1.5 h, and dry at 55 °C for 1.5 h after the reaction to obtain the composite fiber.

[0051] Preparation of phenolic molding compound: Phenolic resin, curing agent and composite fiber are mixed and put into a twin-screw extruder for melt blending treatment, extrusion and molding to obtain phenolic molding compound.

[0052] Comparative Example 1 A composite thermal insulation board, which is different from Example 1 in that glass fiber is used instead of composite fiber.

[0053] Performance test: The flexural strength and impact strength of the phenolic molding compounds prepared in Examples 1-6 and Comparative Example 1 were tested. The flexural strength was measured using an XJ828 digital display flexural strength and tensile machine, referring to the plastic flexural property test method of GB9341-88, with a span of 80 mm and a test speed of 2 mm / min. The impact strength was measured using an HCJ-4J impact testing machine, referring to the simple supported beam impact test method for rigid plastics of GB / T1043-93. The heat resistance performance was tested using an XRW-300 heat distortion temperature measuring instrument, referring to the plastic flexural load heat distortion temperature test method of GB1634-88, with a heating rate of 120 °C / h. The test results are shown in Table 1.

[0054] Table 1

[0055] Referring to Table 1, the flexural strength and impact strength of Example 1 are increased by 60.1% and 59.4% respectively compared with Comparative Example 1. At the same time, the heat distortion temperature of Example 1 is also increased compared with Comparative Example 1. It can be seen that the composite fiber can significantly improve the flexural strength, impact strength and heat resistance performance of the phenolic molding compound compared with the glass fiber. The above are only the preferred embodiments of the present invention and do not impose any form of limitation on the present invention. Although the present invention has been disclosed above with the preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to equivalent variations within the scope of the technical solution of the present invention without departing from the technical solution of the present invention. However, any simple modification, equivalent variation and modification made to the above embodiments based on the technical essence of the present invention still belong to the scope of the technical solution of the present invention.

Claims

1. A phenolic molding compound, characterized in that: The composition comprises the following components by weight: 30-50 parts of phenolic resin, 4-7 parts of curing agent and 3-6 parts of composite fiber; Wherein, the composite fiber is glass fiber with polyurea nanofiber coated on the surface.

2. The phenolic molding compound according to claim 1, characterized in that: In the composite fiber, the diameter of the glass fiber is 8 μm-12 μm.

3. The phenolic molding compound according to claim 1, characterized in that: The polyurea nanofiber is prepared by polymerization reaction of isocyanate and amino compound.

4. The phenolic molding compound according to claim 3, characterized in that: The isocyanate includes at least one of toluene diisocyanate and diphenylmethane diisocyanate, and the amino compound includes at least one of octadecylamine and cyclohexylamine.

5. The method for preparing a phenolic molding compound according to any one of claims 1 to 4, characterized in that: include: The phenolic resin, the curing agent and the composite fiber are mixed, put into a twin-screw extruder, melt-blended, extruded and molded to obtain a phenolic molding compound.

6. The preparation method according to claim 5, characterized in that: The method for preparing the composite fiber comprises: Add glass fiber to the amino compound solution, stir at 40℃-50℃ for 20min-30min, add isocyanate solution, heat to 70℃-80℃, react for 1h-2h, and dry at 50℃-60℃ for 1h-2h after the reaction to obtain composite fiber.

7. The preparation method according to claim 5, characterized in that: The mass ratio of the glass fiber, the amino compound and the isocyanate is 1:1.5-2:0.5-1.

8. The preparation method according to claim 6, characterized in that: Also includes: Before preparing the composite fiber, the glass fiber is subjected to an acid treatment.

9. The preparation method according to claim 8, characterized in that: The acid solution used in the acid treatment is a hydrochloric acid solution with a mass fraction of 5%-10%, and the time of the acid treatment is 10h-20h.

10. The preparation method according to claim 8, characterized in that: Further including: After the acid treatment, the glass fiber is dried for 1 hour to 2 hours at a temperature of 50° C. to 70° C.

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